It took five years, thousands of interviews and several trips around the world before police had enough evidence to bring Malcolm Webster to justice.

The investigation - named Operation Field - saw detectives take statements from more than 1000 people and collect 1200 individual pieces of evidence.

It began when Jane Drumm - the sister of Webster's second intended murder victim, Felicity - raised her own concerns with British police in 2006. The domestic violence expert was at a conference in Britain with several forces when she spoke to officers of her shock at discovering her sister had been in a road accident that seemed to mirror perfectly the "tragic accident" that had claimed Webster's first wife, Claire.

The officers found the similarities deeply disturbing and they contacted Grampian Police.

The inquiry - one of the biggest, longest-running and complex in Grampian Police's history - was led by Detective Chief Inspector Phil Chapman.

He said: "One of the most challenging parts of this inquiry was establishing that a crime had been committed. We began reviewing the circumstances of Claire's death but there were huge challenges in assimilating all of the relevant documentation.

"This incident was always treated as a crime - but the criminal was thought to have been a motorcyclist who left the scene of the crash, not the driver of the car.

"We formed a strategy, which meant looking at liver samples from Claire, and that involved a technique for which there had never been a need before.

"The ultimate outcome was that the sample came back with evidence of benzodiazepines [sedatives] - specifically temazepam - and clearly that was significant for us and for the procurator fiscal, who instructed that on January 15, 2008 the investigation would be opened and we would look at all aspects of the crash to establish that a crime had been committed."

The magnitude of the task was never lost on the detectives, nor was the complexity of establishing that Claire's death was no accident.

Chapman said: "It was about 14 years on - most of the people originally spoken to after Claire's death had moved on and we didn't have original statements for witnesses.

"We had to trace them and re-interview them, bearing in mind many of the witnesses were traumatised by what was, for them, a tragic event in their lives.

"Having received information from the New Zealand authorities, we could see the similarities between what happened over there and the suspected offences in [Britain] involving Claire.

"But going to [speak with] Claire's family wasn't something that I was willing to do, early in the investigation, until I was satisfied there was a case that we could pursue," he said. "We got people - fire and crash investigators, very prominent in their field - to look at the circumstances of the crash involving Claire to see if it could have happened in the way Malcolm had said.

"As it was, the collision experts said it could not have happened the way he told police it had and the fire experts said it could not have occurred in the manner he had claimed.

"That gave us the building blocks to establish we had an individual who said something happened in a manner in which experts said it could not have.

"We then had to build a picture of how it all happened, as well as the motive, looking at information from many years ago. We had to secure medical notes and evidence of Claire's health, insurance policies, bank statements, records of cheques - the list went on.

"We also had to speak to people who had moved to other parts of the world and we sent letters to authorities in countries including France and Sierra Leone to speak to witnesses.

"We also looked at the profile of women Malcolm had been involved with and they were all very similar - articulate and intelligent."

But it was when the detectives began looking into the financial aspects of Webster's life that their suspicions grew - as did the weight of evidence pointing to a horrific crime having been committed.

"At key stages in his life he came into huge amounts of money, invariably when he was in debt," said Chapman. "He got £200,000 after Claire's death but he spent it all in six months. Records showed up to £3000 going out of his account at a time - it was literally like an open tap the way the money went out of his bank account.

"Ultimately we'll never know what he spent all the money on but there were major things, like a yacht and a Land Rover.

"We started to paint a clear picture of someone who had not been the subject of a freak accident but someone who had appeared to have been very calculating and rational in causing an event to satisfy his need for money."

When police contacted Claire's family to reveal they believed her death had been no accident, her mother was not surprised.

"Claire's mum always held a belief that something else had happened and felt there was more to it," Chapman said.

"I think it was quite cathartic for her when we approached her to say we were looking into what happened to Claire. The family was very dignified and said they just wanted the truth."

But when detectives confronted Webster about his suspected crimes, he gave nothing away.

"We spoke to Malcolm and detained him in relation to the murder of Claire. He was very calm, he just said 'no comment'. He exercised his right not to speak and he was very much compliant, just as he had told the media that he would be. He has never been unruly and he allowed us to go about our business, never commenting - but that was his right."

After five long years, the stage was set for one of Scotland's most complex criminal trials in living memory.

Following the guilty verdict, Chapman said: "Malcolm cannot be anything but hugely arrogant. With most homicides, you find that they were spontaneous acts - very rarely do you have a premeditated homicide.

"In Malcolm's case, he considered, planned and executed a specific plan, which shows total contempt for human life. His absolute greed is ultimately what has undone him."

The detective also praised the women who helped ensure Webster was brought to justice.

He said: "All of the women had been duped by Malcolm and it was a real challenge for them to help with the evidence, because they were embarrassed.

"No one wants to admit they've been taken in by a liar - but to admit to be duped in the way they had been by Malcolm was very difficult to come to terms with."

Path to a prison cell
September 3, 1993
Malcolm Webster marries Claire Morris at King's College Chapel, University of Aberdeen.May 28,

Morris dies in a fire after a road smash on the Oldmeldrum to Auchenhuive road, with Webster at the wheel.

Webster meets Felicity Drumm in Saudi Arabia.

April 1997
Malcolm marries Drumm in New Zealand.

May, 1997
The couple leave New Zealand for Scotland, to live at Lyne of Skene.

November 12, 1998
Webster complains about losing cash after his possessions were destroyed in a fire at a Shore Porters facility.

December, 1998
Webster and Drumm return to New Zealand.

February 12, 1999
Drumm survives a crash in New Zealand while Webster is driving in Takapuna, Auckland.

December 2005
Webster begins a relationship with Simone Banerjee in Oban.

March , 2008
Probe of Morris' death revealed.

August 2008
Webster tells a New Zealand newspaper he had nothing to do with Morris' death.

February 2, 2009
Webster appears at Aberdeen Sheriff Court and denies killing Morris.

December 2010
Webster is suspended from his profession for 12 months by the Nursing and Midwifery Council.

February 1, 2011
Webster goes on trial at the High Court in Glasgow, accused of murdering Morris and attempting to murder Drumm.

May 20, 2011
Close to the 17th anniversary of Morris' death, Webster is found guilty of her murder.

Gavin Roberts is a crime reporter on the Aberdeen Evening Express.